RE123-based oxide superconductors are formed in a composition expressed by RE1Ba2Cu3O7−x (RE: rare earth element, such as Y or Gd), and have a critical temperature higher than a liquid nitrogen temperature (77K). Studies have been conducted in many places to apply these oxide superconductive conductors to a superconducting magnet or various superconducting devices, such as a transformer, a fault current limiter, and a motor.
In order to use oxide superconductors in various superconducting devices, in general, an oxide superconductor is worked into a wire, and is used as a conductor of electric power supply or an oxide superconducting wire, such as a magnetic coil. Specifically, an oxide superconducting wire in which an oxide superconducting tape with an Ag layer provided on the surface of an oxide superconductor layer is bonded to a stabilizer tape (stabilization layer) with solder interposed therebetween is known. The Ag layer is provided on the surface of the oxide superconducting layer, whereby it is possible to protect the oxide superconducting layer and to suppress deterioration of the oxide superconducting layer due to moisture.
However, if the solder is bonded to the Ag layer, an alloy layer is formed at the interface between the Ag layer and the solder and electric stability is degraded. Furthermore, since Ag is embrittled due to alloying and is deteriorated in strength, there is a problem in that the stabilization layer is separated from the Ag layer.
Accordingly, in Patent Document 1, a plated layer made of an alloy of Cu or the like is provided on an Ag layer, and contact of the Ag layer and solder is limited to suppress embrittlement of Ag.